The invention is particularly concerned with liquid analyzers of the type known in the industry in which ozone, an acid, a base are at different times mixed with a liquid sample in a reactor vessel. For example the liquid sample may be oxidized using a base solution and ozone. An acid may be added to the liquid sample, followed by sparging to remove carbonate. Also, a catalyst may be added to the liquid sample for reducing oxalate to carbonate.
The invention does however have more widespread use in applications where it is necessary to mix a gas with a liquid or separate a gas from the liquid. A gas can be mixed with a liquid by simply bubbling the gas through the liquid. Where more aggressive mixing is required, usually such mixing takes place with the aid of a pump whereby the liquid and gas mixture is extracted from a chamber through a pump and circulated back to the chamber. Typically valves such as “flapper” valves are provided on the pump to control the flow of the liquid and gas mixture through the pump. However, particulate material or small fibres can block the valves thus adversely affecting the mixing of the gas and the liquid.
JP62132530, U.S. Pat. No. 5,934,885, and JP6047165 all describe arrangements for mixing of liquids. In JP62132530 membranes are used for flow control of two liquids to be mixed. U.S. Pat. No. 5,934,885 describes a multi-layered reagent pump assembly having diaphragm pumps disposed between the layers. JP6047265 describes a mixer having a vibrating diaphragm in a mixing chamber for dispersing a gas in a liquid.
The invention is directed towards providing an improved agitator for applications such as described above. One objective is to achieve efficient mixing of quantities below about 25 liters while avoiding moving parts which can become blocked by particles or fibres, such as valves and pumps with rotating vanes. Another objective is to achieve improved agitation in a situation where the gas which is introduced may be quickly changed. A further objective is to avoid need for pump seals. A further objective is to allow operation in an aggressive environment.
The present embodiments meet these objectives.
The present embodiments are detailed below with reference to the listed Figures.